Pulsation Dampeners for Centrifugal Pumps
Choosing Shock Stop Bottles, check list:- "Water Hammer Alleviator Work Sheet" Meeting the Safe Use Requirements of the EC Pressure Equipment Directive. For shock, "water hammer" , backflow cavity implosion, etc., it is not possible to pre-select the solution.
1. Centrifugal Pump Acoustics
2. Pump Start-Up Surge
3. Shut-Down Back-Flow Bang
4. Rapid Valve Closure Hammer
5. Reasons for Levels of Smoothness
"Pump Start-Up Surge"
Acceleration head to overcome the mass in the pipe system after the pump.
Please at the least review 17, 6, 7, 10, 11, 15, 16, + 24, & 25. and answer:
1. Nitrogen or air pad pressure in top of tank, bars
2. Positive suction head
3. Negative suction head
4. Diameter of the suction line
5. Pressure losses, filters, etc.
6. How long after pump start does the spill back loop valve close
7. Time taken for pump start
8. Any increase in elevation
9. Any decrease in elevation
10. Average discharge pipe diameter
11. Length of discharge pipe
12. Pressure against which the system is discharging
13. Pipe wall dilatability (wall elasticity kills shock)
14. Liquid compressibility (more system cushioning)
15. Any compatible elastomers
16. Compatible metals
17. Rate of mass transfer kg/sec or SG & GPM
18. Viscosity cP
19. R.P.M.
20. Impeller diameter
21. Metal
22.
23. Minimum design metal temperature – mdmt
24. Design temperature
25. Design pressure
26. Max diameter
27. Max height
28. Connection type |
Pump Shut-Down "Back Flow Bang"
The mass and velocity of return, filling the void that was caused by continuing to flow away from the pump after it was stopped.
Please at the least review 17, 6, 7, 10, 11, 15, 16, + 24, & 25 and answer:-
1. Nitrogen or air pad pressure in top of tank, bars
2. net Positive suction head
Negative suction head
3. The length of the suction line
4. Diameter of the suction line
5. Pressure losses, filters, etc.
6. Time for valve to open after pump is turned off
7. Time taken for pump to spin down
8. Any increase in elevation
9. Any decrease in elevation
10. Average discharge pipe diameter
11. Length of discharge pipe
12. Pressure against which the system is discharging
13. Pipe wall dilatability (wall elasticity kills shock)
14. Liquid compressibility (more system cushioning)
15. Any compatible elastomers
16. Compatible metals
17. Rate of mass transfer when pump ran kg/sec or SG & GPM
18. Viscosity cP
19. R.P.M.
20. Impeller diameter
21. Metal
22.
23. Minimum design metal temperature – mdmt
24. Design temperature
25. Design pressure
26. Max diameter
27. Max height
28. Connection type |
Fast Valve Closure - "Valve Slam Hammer"
Deceleration of the mass of liquid in the pipe in a small amount of time.
Please at the least review 17, 6, 7, 10, 11, 15, 16, + 24, & 25 and answer:-
1. Nitrogen or air pad pressure in top of tank, bars
2. net Positive suction head
Negative suction head
3. The length of the suction line
4. Diameter of the suction line
5. Pressure losses, filters, etc.
6. Time taken for valve closure
7. Time taken for pump to spin down
8. Any increase in elevation
9. Any decrease in elevation
10. Average discharge pipe diameter
11. Length of discharge pipe
12. Pressure against which the system is discharging
13. Pipe wall dilatability (wall elasticity kills shock)
14. Liquid compressibility (more system cushioning)
15. Any compatible elastomers
16. Compatible metals
17. Rate of mass transfer kg/sec or SG & GPM
18. Viscosity cP
19. R.P.M.
20. Impeller diameter
21. Metal
22.
23. Minimum design metal temperature – mdmt
24. Design temperature
25. Design pressure
26. Max diameter
27. Max height
28. Connection type |
Stop Drive belt break-up, keep instant load changes less than 14%. To stop tooth chatter wear, depending on machine inertia, keeps pressure transients less than 12%. To Stop premature Lift & "weeping", keep all pressure waves that are sustained for in excess of 40 ms below 9% less than static set pressure. Prevent bust disk fatigue, by keeping repetitive spikes to less than + / - 4% of steady state pressure. If in doubt stay below 5psi transient over pressure to stop pipe fatigue. Examples: 25 ft of 1" pipe with a 100 Hz frequency. Keep the shocks below 10 psi 6500 ft of 20" @ 0.5 Hz, keep below 30 psi.
Suitability for purpose recommendations made on the basis of data & calculations above are with the following normal responsibilities of the parties: System Design, S.D. to consider, Pump Vendor, Bottle Peddler
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Impelling Pumps
Screw
Reciprocating Pumps
Air Operated Double Diaphragm | Dosing | Injection | Metering | Plunger / Piston | Power
Rotary Pumps
Centrifugal | Gear | Lobe | Vane
Other Pump Types
Hose / Peristaltic | Progressive Cavity
Pulsation dampeners are designed to address pressure pulsation, which is caused by the resistance of the system to flow. Therefore our pulsation dampeners focus on the system related responsibility and are less related to pump liability. PUMPS make FLOW, SYSTEMS cause PRESSURE, pressure pulsation is a system response, AND a system responsibility NOT a pump manufacturers liability. When you see a pulsation dampener or a pump of particular interest, please request literature dedicated to that subject.
"Dampeners that do, flow goes through, but pressure pulsation does not." |
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